This is a note to let you know that I've just added the patch titled
hwmon: (bt1-pvt) Wait for the completion with timeout
to the 5.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hwmon-bt1-pvt-wait-for-the-completion-with-timeout.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 63d56e541a2357052a6ec0f856711f5d0ce3a6eb
Author: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Date: Sun Sep 20 14:09:23 2020 +0300
hwmon: (bt1-pvt) Wait for the completion with timeout
[ Upstream commit 0ffd21d5985506d164ada9e8fff6daae8ef469a1 ]
If the PVT sensor is suddenly powered down while a caller is waiting for
the conversion completion, the request won't be finished and the task will
hang up on this procedure until the power is back up again. Let's call the
wait_for_completion_timeout() method instead to prevent that. The cached
timeout is exactly what we need to predict for how long conversion could
normally last.
Fixes: 87976ce2825d ("hwmon: Add Baikal-T1 PVT sensor driver")
Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200920110924.19741-4-Sergey.Semin@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/hwmon/bt1-pvt.c b/drivers/hwmon/bt1-pvt.c
index 2600426a3b21c..3e1d56585b91a 100644
--- a/drivers/hwmon/bt1-pvt.c
+++ b/drivers/hwmon/bt1-pvt.c
@@ -477,6 +477,7 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
long *val)
{
struct pvt_cache *cache = &pvt->cache[type];
+ unsigned long timeout;
u32 data;
int ret;
@@ -500,7 +501,14 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
pvt_update(pvt->regs + PVT_INTR_MASK, PVT_INTR_DVALID, 0);
pvt_update(pvt->regs + PVT_CTRL, PVT_CTRL_EN, PVT_CTRL_EN);
- wait_for_completion(&cache->conversion);
+ /*
+ * Wait with timeout since in case if the sensor is suddenly powered
+ * down the request won't be completed and the caller will hang up on
+ * this procedure until the power is back up again. Multiply the
+ * timeout by the factor of two to prevent a false timeout.
+ */
+ timeout = 2 * usecs_to_jiffies(ktime_to_us(pvt->timeout));
+ ret = wait_for_completion_timeout(&cache->conversion, timeout);
pvt_update(pvt->regs + PVT_CTRL, PVT_CTRL_EN, 0);
pvt_update(pvt->regs + PVT_INTR_MASK, PVT_INTR_DVALID,
@@ -510,6 +518,9 @@ static int pvt_read_data(struct pvt_hwmon *pvt, enum pvt_sensor_type type,
mutex_unlock(&pvt->iface_mtx);
+ if (!ret)
+ return -ETIMEDOUT;
+
if (type == PVT_TEMP)
*val = pvt_calc_poly(&poly_N_to_temp, data);
else
